A developing cartridge including: a developing part having a developer bearing member; a developer container which is constituted by coupling a container body having an opening part and a developer supplying port, and a lid member for closing the opening part, and which houses developer therein; and a developer stirring member which stirs the developer inside this developer container and supplies the developer to the developer bearing member, wherein the shape and the capacity of the developer container are changed by changing the shape of the lid member.